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      <td><p class="toc level1"><a href="docinfo.html">Document Information</a></p>
<p class="toc level1 tocsp"><a href="gexaf.html">Preface</a></p>
<p class="toc level1 tocsp"><a href="gfirp.html">Part&nbsp;I&nbsp;Introduction</a></p>
<p class="toc level2"><a href="bnaaw.html">1.&nbsp;&nbsp;Overview</a></p>
<p class="toc level2"><a href="gfiud.html">2.&nbsp;&nbsp;Using the Tutorial Examples</a></p>
<p class="toc level1 tocsp"><a href="bnadp.html">Part&nbsp;II&nbsp;The Web Tier</a></p>
<p class="toc level2"><a href="bnadr.html">3.&nbsp;&nbsp;Getting Started with Web Applications</a></p>
<p class="toc level2"><a href="bnafd.html">4.&nbsp;&nbsp;Java Servlet Technology</a></p>
<p class="toc level2"><a href="bnagx.html">5.&nbsp;&nbsp;JavaServer Pages Technology</a></p>
<p class="toc level2"><a href="bnajo.html">6.&nbsp;&nbsp;JavaServer Pages Documents</a></p>
<p class="toc level2"><a href="bnakc.html">7.&nbsp;&nbsp;JavaServer Pages Standard Tag Library</a></p>
<p class="toc level2"><a href="bnalj.html">8.&nbsp;&nbsp;Custom Tags in JSP Pages</a></p>
<p class="toc level2"><a href="bnaon.html">9.&nbsp;&nbsp;Scripting in JSP Pages</a></p>
<p class="toc level2"><a href="bnaph.html">10.&nbsp;&nbsp;JavaServer Faces Technology</a></p>
<p class="toc level2"><a href="bnaqz.html">11.&nbsp;&nbsp;Using JavaServer Faces Technology in JSP Pages</a></p>
<p class="toc level2"><a href="bnatx.html">12.&nbsp;&nbsp;Developing with JavaServer Faces Technology</a></p>
<p class="toc level2"><a href="bnavg.html">13.&nbsp;&nbsp;Creating Custom UI Components</a></p>
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<p class="toc level3"><a href="">Determining Whether You Need a Custom Component or Renderer</a></p>
<p class="toc level4"><a href="#bnavi">When to Use a Custom Component</a></p>
<p class="toc level4"><a href="#bnavj">When to Use a Custom Renderer</a></p>
<p class="toc level4"><a href="#bnavk">Component, Renderer, and Tag Combinations</a></p>
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<p class="toc level3 tocsp"><a href="bnavm.html">Understanding the Image Map Example</a></p>
<p class="toc level4"><a href="bnavm.html#bnavn">Why Use JavaServer Faces Technology to Implement an Image Map?</a></p>
<p class="toc level4"><a href="bnavm.html#bnavo">Understanding the Rendered HTML</a></p>
<p class="toc level4"><a href="bnavm.html#bnavp">Understanding the JSP Page</a></p>
<p class="toc level4"><a href="bnavm.html#bnavq">Configuring Model Data</a></p>
<p class="toc level4"><a href="bnavm.html#bnavr">Summary of the Application Classes</a></p>
<p class="toc level3 tocsp"><a href="bnavt.html">Steps for Creating a Custom Component</a></p>
<p class="toc level3"><a href="bnavu.html">Creating Custom Component Classes</a></p>
<p class="toc level4"><a href="bnavu.html#bnavv">Specifying the Component Family</a></p>
<p class="toc level4"><a href="bnavu.html#bnavw">Performing Encoding</a></p>
<p class="toc level4"><a href="bnavu.html#bnavx">Performing Decoding</a></p>
<p class="toc level4"><a href="bnavu.html#bnavy">Enabling Component Properties to Accept Expressions</a></p>
<p class="toc level4"><a href="bnavu.html#bnavz">Saving and Restoring State</a></p>
<p class="toc level3 tocsp"><a href="bnawa.html">Delegating Rendering to a Renderer</a></p>
<p class="toc level4"><a href="bnawa.html#bnawb">Creating the Renderer Class</a></p>
<p class="toc level4"><a href="bnawa.html#bnawc">Identifying the Renderer Type</a></p>
<p class="toc level3 tocsp"><a href="bnawd.html">Handling Events for Custom Components</a></p>
<p class="toc level3"><a href="bnawe.html">Creating the Component Tag Handler</a></p>
<p class="toc level4"><a href="bnawe.html#bnawf">Retrieving the Component Type</a></p>
<p class="toc level4"><a href="bnawe.html#bnawg">Setting Component Property Values</a></p>
<p class="toc level5"><a href="bnawe.html#bnawh">Getting the Attribute Values</a></p>
<p class="toc level5"><a href="bnawe.html#bnawi">Setting the Component Property Values</a></p>
<p class="toc level4 tocsp"><a href="bnawe.html#bnawl">Providing the Renderer Type</a></p>
<p class="toc level4"><a href="bnawe.html#bnawm">Releasing Resources</a></p>
<p class="toc level3 tocsp"><a href="bnawn.html">Defining the Custom Component Tag in a Tag Library Descriptor</a></p>
<p class="toc level2 tocsp"><a href="bnawo.html">14.&nbsp;&nbsp;Configuring JavaServer Faces Applications</a></p>
<p class="toc level2"><a href="bnaxu.html">15.&nbsp;&nbsp;Internationalizing and Localizing Web Applications</a></p>
<p class="toc level1 tocsp"><a href="bnayk.html">Part&nbsp;III&nbsp;Web Services</a></p>
<p class="toc level2"><a href="bnayl.html">16.&nbsp;&nbsp;Building Web Services with JAX-WS</a></p>
<p class="toc level2"><a href="bnazf.html">17.&nbsp;&nbsp;Binding between XML Schema and Java Classes</a></p>
<p class="toc level2"><a href="bnbdv.html">18.&nbsp;&nbsp;Streaming API for XML</a></p>
<p class="toc level2"><a href="bnbhf.html">19.&nbsp;&nbsp;SOAP with Attachments API for Java</a></p>
<p class="toc level1 tocsp"><a href="bnblr.html">Part&nbsp;IV&nbsp;Enterprise Beans</a></p>
<p class="toc level2"><a href="bnbls.html">20.&nbsp;&nbsp;Enterprise Beans</a></p>
<p class="toc level2"><a href="bnbnb.html">21.&nbsp;&nbsp;Getting Started with Enterprise Beans</a></p>
<p class="toc level2"><a href="bnboc.html">22.&nbsp;&nbsp;Session Bean Examples</a></p>
<p class="toc level2"><a href="bnbpk.html">23.&nbsp;&nbsp;A Message-Driven Bean Example</a></p>
<p class="toc level1 tocsp"><a href="bnbpy.html">Part&nbsp;V&nbsp;Persistence</a></p>
<p class="toc level2"><a href="bnbpz.html">24.&nbsp;&nbsp;Introduction to the Java Persistence API</a></p>
<p class="toc level2"><a href="bnbrl.html">25.&nbsp;&nbsp;Persistence in the Web Tier</a></p>
<p class="toc level2"><a href="bnbrs.html">26.&nbsp;&nbsp;Persistence in the EJB Tier</a></p>
<p class="toc level2"><a href="bnbtg.html">27.&nbsp;&nbsp;The Java Persistence Query Language</a></p>
<p class="toc level1 tocsp"><a href="bnbwi.html">Part&nbsp;VI&nbsp;Services</a></p>
<p class="toc level2"><a href="bnbwj.html">28.&nbsp;&nbsp;Introduction to Security in the Java EE Platform</a></p>
<p class="toc level2"><a href="bnbyk.html">29.&nbsp;&nbsp;Securing Java EE Applications</a></p>
<p class="toc level2"><a href="bncas.html">30.&nbsp;&nbsp;Securing Web Applications</a></p>
<p class="toc level2"><a href="bncdq.html">31.&nbsp;&nbsp;The Java Message Service API</a></p>
<p class="toc level2"><a href="bncgv.html">32.&nbsp;&nbsp;Java EE Examples Using the JMS API</a></p>
<p class="toc level2"><a href="bncih.html">33.&nbsp;&nbsp;Transactions</a></p>
<p class="toc level2"><a href="bncjh.html">34.&nbsp;&nbsp;Resource Connections</a></p>
<p class="toc level2"><a href="bncjx.html">35.&nbsp;&nbsp;Connector Architecture</a></p>
<p class="toc level1 tocsp"><a href="bnckn.html">Part&nbsp;VII&nbsp;Case Studies</a></p>
<p class="toc level2"><a href="bncko.html">36.&nbsp;&nbsp;The Coffee Break Application</a></p>
<p class="toc level2"><a href="bnclz.html">37.&nbsp;&nbsp;The Duke's Bank Application</a></p>
<p class="toc level1 tocsp"><a href="gexbq.html">Part&nbsp;VIII&nbsp;Appendixes</a></p>
<p class="toc level2"><a href="bncno.html">A.&nbsp;&nbsp;Java Encoding Schemes</a></p>
<p class="toc level2"><a href="bncnq.html">B.&nbsp;&nbsp;Preparation for Java EE Certification Exams</a></p>
<p class="toc level2"><a href="bncnt.html">C.&nbsp;&nbsp;About the Authors</a></p>
<p class="toc level1 tocsp"><a href="idx-1.html">Index</a></p>
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<a name="bnavh"></a><h3>Determining Whether You Need a Custom Component or Renderer</h3>
<p>The JavaServer Faces implementation supports a rich set of components and associated renderers,
which are enough for most simple applications. This section helps you decide whether
you need a custom component or custom renderer or instead can use a
standard component and renderer.</p>

<a name="bnavi"></a><h4>When to Use a Custom Component</h4>
<a name="indexterm-1460"></a><p><a name="indexterm-1461"></a>A component class defines the state and behavior of a UI component. This
behavior includes converting the value of a component to the appropriate markup, queuing
events on components, performing validation, and other functionality.</p><p>You need to create a custom component in these situations:</p>
<ul><li><p>You need to add new behavior to a standard component, such as generating an additional type of event.</p></li>
<li><p>You need to aggregate components to create a new component that has its own unique behavior. The new component must be a custom component. One example is a date chooser component consisting of three drop-down lists.</p></li>
<li><p>You need a component that is supported by an HTML client but is not currently implemented by JavaServer Faces technology. The current release does not contain standard components for complex HTML components, such as frames; however, because of the extensibility of the component architecture, you can use JavaServer Faces technology to create components like these.</p></li>
<li><p>You need to render to a non-HTML client that requires extra components not supported by HTML. Eventually, the standard HTML render kit will provide support for all standard HTML components. However, if you are rendering to a different client, such as a phone, you might need to create custom components to represent the controls uniquely supported by the client. For example, some component architectures for wireless clients include support for tickers and progress bars, which are not available on an HTML client. In this case, you might also need a custom renderer along with the component; or you might need only a custom renderer.</p></li></ul>
<p>You do not need to create a custom component in these cases:</p>
<ul><li><p><a name="indexterm-1462"></a>You simply need to manipulate data on the component or add application-specific functionality to it. In this situation, you should create a backing bean for this purpose and bind it to the standard component rather than create a custom component. See <a href="bnaqm.html">Backing Beans</a> for more information on backing beans.</p></li>
<li><p>You need to convert a component&rsquo;s data to a type not supported by its renderer. See <a href="bnast.html">Using the Standard Converters</a> for more information about converting a component&rsquo;s data.</p></li>
<li><p>You need to perform validation on the component data. Standard validators and custom validators can be added to a component by using the validator tags from the page. See <a href="bnatc.html">Using the Standard Validators</a> and <a href="bnauw.html">Creating a Custom Validator</a> for more information about validating a component&rsquo;s data.</p></li>
<li><p><a name="indexterm-1463"></a><a name="indexterm-1464"></a><a name="indexterm-1465"></a>You need to register event listeners on components. You can either register event listeners on components using the <tt>valueChangeListener</tt> and <tt>actionListener</tt> tags, or you can point at an event-processing method on a backing bean using the component&rsquo;s <tt>actionListener</tt> or <tt>valueChangeListener</tt> attributes. See <a href="bnaut.html">Implementing an Event Listener</a> and <a href="bnavb.html">Writing Backing Bean Methods</a> for more information.</p></li></ul>


<a name="bnavj"></a><h4>When to Use a Custom Renderer</h4>
<a name="indexterm-1466"></a><p>If you are creating a custom component, you need to ensure, among
other things, that your component class performs these operations:</p>
<ul><li><p><a name="indexterm-1467"></a><b>Decoding</b>: Converting the incoming request parameters to the local value of the component</p></li>
<li><p><a name="indexterm-1468"></a><b>Encoding</b>: Converting the current local value of the component into the corresponding markup that represents it in the response</p></li></ul>
<p>The JavaServer Faces specification supports two programming models for handling encoding and decoding:</p>
<ul><li><p><a name="indexterm-1469"></a><b>Direct implementation</b>: The component class itself implements the decoding and encoding.</p></li>
<li><p><a name="indexterm-1470"></a><b>Delegated implementation</b>: The component class delegates the implementation of encoding and decoding to a separate renderer.</p></li></ul>
<p>By delegating the operations to the renderer, you have the option of associating
your custom component with different renderers so that you can represent the component
in different ways on the page. If you don&rsquo;t plan to render a
particular component in different ways, it&rsquo;s simpler to let the component class handle
the rendering.</p><p>If you aren&rsquo;t sure whether you will need the flexibility offered by separate
renderers but you want to use the simpler direct-implementation approach, you can actually
use both models. Your component class can include some default rendering code, but
it can delegate rendering to a renderer if there is one.</p>

<a name="bnavk"></a><h4>Component, Renderer, and Tag Combinations</h4>
<a name="indexterm-1471"></a><p>When you create a custom component, you will usually create a custom renderer
to go with it. You will also need a custom tag to
associate the component with the renderer and to reference the component from the
page.</p><p>In rare situations, however, you might use a custom renderer with a standard
component rather than a custom component. Or you might use a custom tag
without a renderer or a component. This section gives examples of these situations
and summarizes what&rsquo;s required for a custom component, renderer, and tag.</p><p>You would use a custom renderer without a custom component if you
wanted to add some client-side validation on a standard component. You would implement the
validation code with a client-side scripting language, such as JavaScript, and then render
the JavaScript with the custom renderer. In this situation, you need a custom
tag to go with the renderer so that its tag handler can register
the renderer on the standard component.</p><p>Custom components as well as custom renderers need custom tags associated with them.
However, you can have a custom tag without a custom renderer or custom
component. For example, suppose that you need to create a custom validator that
requires extra attributes on the validator tag. In this case, the custom tag
corresponds to a custom validator and not to a custom component or
custom renderer. In any case, you still need to associate the custom tag
with a server-side object.</p><p><a href="#bnavl">Table&nbsp;13-1</a> summarizes what you must or can associate with a custom component, custom
renderer, or custom tag.</p><a name="bnavl"></a><h6>Table&nbsp;13-1 Requirements for Custom Components, Custom Renderers, and Custom Tags</h6><table><col width="20%"><col width="40%"><col width="39%"><tr><th align="left" valign="top" scope="column"><p>Custom Item</p></th>
<th align="left" valign="top" scope="column"><p>Must Have</p></th>
<th align="left" valign="top" scope="column"><p>Can Have</p></th>
</tr>
<tr><td align="left" valign="top" scope="row"><p>Custom component</p></td>
<td align="left" valign="top" scope="row"><p>Custom tag</p></td>
<td align="left" valign="top" scope="row"><p>Custom renderer or standard renderer</p></td>
</tr>
<tr><td align="left" valign="top" scope="row"><p>Custom
renderer</p></td>
<td align="left" valign="top" scope="row"><p>Custom tag</p></td>
<td align="left" valign="top" scope="row"><p>Custom component or standard component</p></td>
</tr>
<tr><td align="left" valign="top" scope="row"><p>Custom JavaServer Faces tag</p></td>
<td align="left" valign="top" scope="row"><p>Some server-side object, like
a component, a custom renderer, or custom validator</p></td>
<td align="left" valign="top" scope="row"><p>Custom component or standard component associated
with a custom renderer</p></td>
</tr>
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